In the course of current development taking place, communications systems and control thereof are becoming increasingly decentralized. In this regard, a communications system is split into individual subsystems coupled via a communications network, such as a local area network (LAN) or a network based on an internet protocol (IP). This allows, by way of example, components of a relatively large exchange to be distributed over a communications network.
Contemporary communications systems normally provide a large number of communications services and service features. For some of these communications services and service features, such as for “CBO services” (continuous bit stream operation), which include fax, modem, voice and video transmissions, it is necessary for the respective communications system components involved to be in sync for communications data which are to be transmitted.
Arrangements for synchronizing communications system components coupled via a communications network are known in communications networks using direct SDH (synchronous digital hierarchy) or PDH (plesiochronous digital hierarchy) based transmission; e.g.; from section 8 of ITU-T recommendation G.803 and the references indicated therein. In this case, a reference clock is transmitted to the communications system components which are to be synchronized on the physical layer of the transmission protocol used. However, transmitting a reference clock in the physical layer requires continuous layer 1 connections to the individual communications system components. As such, relatively complex communications network structures can be produced only with a great deal of effort, however. In communications networks which can be configured more flexibly, such as local area networks (LAN) or internet protocol based networks, continuous layer 1 connections generally are not provided.
It is an object of the present invention to specify a system which is more flexible than the prior art in order to synchronize communications system components coupled via a communications network for communications data which are to be transmitted.